ladybird/Libraries/LibWeb/HTML/TextMetrics.idl

// https://html.spec.whatwg.org/multipage/canvas.html#textmetrics
[Exposed=(Window,Worker)]
interface TextMetrics {
    // x-direction
    readonly attribute double width; // advance width
    readonly attribute double actualBoundingBoxLeft;
    readonly attribute double actualBoundingBoxRight;

    // y-direction
    readonly attribute double fontBoundingBoxAscent;
    readonly attribute double fontBoundingBoxDescent;
    readonly attribute double actualBoundingBoxAscent;
    readonly attribute double actualBoundingBoxDescent;
    readonly attribute double emHeightAscent;
    readonly attribute double emHeightDescent;
    readonly attribute double hangingBaseline;
    readonly attribute double alphabeticBaseline;
    readonly attribute double ideographicBaseline;
};